CHANTILLY, Va. - The Sheet Metal and Air Conditioning Contractors' National Association (SMACNA) has announced that a public review draft of "HVAC Duct Construction Standards – Metal and Flexible," third edition, is available on the SMACNA Web site for review and comment through Oct. 15, 2005.

SMACNA says the primary goals for the third edition were to change and reorganize the standard to be more user-friendly and include additional construction details that have been requested since the publication of the second edition.

Some of the changes in the new edition include:

A new engineering and design chapter that is directed primarily to design professionals;

New double-wall construction details for round and rectangular ductwork;

New casing construction details;

Expanded pressure class tables to include selections not available in the second edition; and

New figures highlighting the conditions of use and limitations for transverse joints, longitudinal seams, and external reinforcements.

For more information, visit www.smacna.org.

Publication date: 09/12/2005